Changing the default boot partition (solved)

<3 · Veteran Joined: 21 Oct 2004 Posts: 1081

I have a dual boot Gentoo Linux & Windows 7 computer. As some of you may know, recently Microsoft has required that some critical updates for Windows to check that the windows partition is the default boot partition before installing, if that partition is not the default partition the critical update will not install and your computer will reboot with an error message and will then start automatically uninstalling. That means in order to install these patches I need to set the windows partition and the boot partition. I have tried to do this using the KDE partition Manager (KDE frontend for parted) [I disabled the boot flag on the grub2 partition and enabled it on the Windows partition]. For some reason my computer still boots to GRUB instead of directly to Windows. Can someone please tell me how to set my Windows partition to be the default partition? Also I need to revert thing thing back to the way they were after these Windows updates are installed so that grub2 is boot manager after I'm finished.

BonezTheGoon · Posted: Tue May 16, 2017 1:46 pm Post subject:

Going to need some more details. Specifically are these both on the same disk? If not then physically disconnect your Gentoo disk during the process and then reconnect it when done.

If they are on the same disk please provide partition layout details.
_________________

John R. Graham · Posted: Tue May 16, 2017 5:16 pm Post subject:

Moved from Off the Wall to Other Things Gentoo as it really is a Gentoo-related technical support question and I think it warrants a larger technical audience than OTW provides.

- John
_________________
I can confirm that I have received between 0 and 499 National Security Letters.

<3 · Veteran Joined: 21 Oct 2004 Posts: 1081

Both OSes are on the same drive I will post partition information when I get back on that computer.

Jaglover · Posted: Tue May 16, 2017 7:24 pm Post subject:

You have to figure out what is "Windows default boot partition" for Windows. Not really a Linux or Gentoo question at all.
_________________
My Gentoo installation notes.
Please learn how to denote units correctly!

szatox · Advocate Joined: 27 Aug 2013 Posts: 3137

Doesn't windows install its bootloader directly in MBR?
Deactivate all partitions and bios will go for MBR.
And actually... What partition table do you use? MBR or GPT?
Do you use a proper tool for your partition table? Like in, tools that are good with mbr-style do not necessarily even support GPT, and GPT tools don't have to be particularly good at manipulating MBR (though they _should_ fail safe...)
It's good habit to provide some basic information about your setup in advance, perhaps someone will know what to do next, even though this problem doesn't really fit this forum.

jonathan183 · Guru Joined: 13 Dec 2011 Posts: 318

charles17 · Advocate Joined: 02 Mar 2008 Posts: 3664

<3 · Veteran Joined: 21 Oct 2004 Posts: 1081

<3 · Veteran Joined: 21 Oct 2004 Posts: 1081

here is the fdisk printout of the partitions on the hard drive I am using.

krinn · Watchman Joined: 02 May 2003 Posts: 7470

the short boot flag option explains
when your computer boot, the bios look at disk mbr to load the bootloader
the first one found is run. bios work end there.

if no bootloader is found, bios then look for first partition with bootflag enable and then try kick the bootloader from that partition. if none is found result depend on bios, it vary from just staying stuck to a message or offer to reboot...

anyway, windows bootloader is set on a partition
grub could be set on partition, but also in the disk mbr

if you set grub in the disk mbr, then bios run grub, and story end, bios is done, no bootflag is use.
if you set windows partition with the bootflag, but grub is in mbr, the bootflag is of no use for the bios
bios start grub, and default partition to boot depend on grub.

if your windows update really stupidly need it, just set bootflag over its partition so it will be happy, for bios it won't change a thing, it will found grub in mbr and run it
for grub it won't change a thing, grub don't care about bootflag, the bootflag for grub is 'root' (the grub command, not / the partition)
set bootflag to partition sda2, windows use a small partition now so it must that one.

nothing will change for you, and your windows update will be happy (if you correctly assume it just need the bootflag set)

<3 · Veteran Joined: 21 Oct 2004 Posts: 1081

I am sorry krinn, I don't mean to be rude but I don't understand what you said.

Tony0945 · Posted: Sat May 20, 2017 1:49 am Post subject:

Don't know if it works for win 7 because there is considerable change, but for XP, I let windows do it's thing, then install grub (legacy, maybe it won't work for grub 2) in the boot partition, not the mbr. Then dd is used to create a boot.lnx file. The Windows boot menu is editted to boot from that file as a choice. Windows had provided that avenue to allow dual booting with Win 98. It's a Windows method so Windows won't object.

That "security feature" is probably checking the mbr and thinks that grub is a rootkit.

I'll post details if someone can confirm that this works with win 7. I don't want to give instructions that will trash your computer.

krinn · Watchman Joined: 02 May 2003 Posts: 7470

<3 · Veteran Joined: 21 Oct 2004 Posts: 1081

yes, that is what I thought. Some people could take what I said as being rude. So anyways how do I make the windows boot manager the default?

Tony0945 · Posted: Sat May 20, 2017 10:34 pm Post subject:

sda3 should not have the bootflag on. sda1 should.

This is because grub doesn't care about bootflags but windows does. You can change the bootflag with gparted. Select the sda1 partition and in the menu, click "manage flags". The rest is obvious.

You still may have to change the MBR, but first see if the boot flag satisfies Windows.

<3 · Veteran Joined: 21 Oct 2004 Posts: 1081

Yes when I had set sda1 as bootable grub still booted. How do I change the mbr

The Doctor · Moderator Joined: 27 Jul 2010 Posts: 2678

You would have to boot into windows and have it reinstall its boot loader. This will nuke grub.
_________________
First things first, but not necessarily in that order.

Apologies if I take a while to respond. I'm currently working on the dematerialization circuit for my blue box.

jonathan183 · Guru Joined: 13 Dec 2011 Posts: 318

Tony0945 · Posted: Sun May 21, 2017 11:52 am Post subject:

Apparently, win 7 uses the same boot procedure as XP. Micro$oft just made it more hidden. In XP you can edit the file, boot.ini, with any text editor. Win 7 requires a more complex procedure. For one thing, they seem to have renamed boot.ini. You can google for "boot linux from windows 7 bootloader". Most responses recommend using a freeware tool called EasyBCD. I have never used this so I hesitate to recommend that you download and run it.

For XP and Win2000, you install grub into a partition rather than the MBR. Then you make a copy of the first 512 bytes using dd.

Hu · Moderator Joined: 06 Mar 2007 Posts: 21635

Starting in Windows Vista, and presumably applying to all newer systems, you can use the command line tool bcdedit to manipulate the Windows boot configuration. If I recall correctly, this tool is shipped by Microsoft as part of the base system. It may not be as nice as other editors, but it will let you make the required changes without installing add-on software.

Tony0945 · Posted: Sun May 21, 2017 3:53 pm Post subject:

Thank you, Hu. I have win 7 on one computer but do very little with it. Of the "new technology" Windows versions, I preferred win 2000. After that point, a concerted effort was made to hide the fact that it is an OS running on a computer, not just an "app platform".

Apparently, from reviews, this EasyBCD is easier to use than the raw Windows interface. I preferred just running notepad on C:\boot.ini, but Microsoft doesn't like it to be easy. they want it to be hard so that the user will unquestioningly accept whatever they say.

There is some controversy about this thread in "Report violations ...", but I think that the more we know, the better. The OP has reported what seems to me to be an effort by Micro$oft to keep everything but Window$ off of computers and we have to fight back by helping newbies to ease into Linux. Besides, not everything will run on Linux and Wine seems to be regressing except for games.

<3 · Veteran Joined: 21 Oct 2004 Posts: 1081

Really? someone reported this thread to the mods?

krinn · Watchman Joined: 02 May 2003 Posts: 7470

reporting a thread doesn't mean anyone wants your death
and as the report is about "user is speaking about a windows problem", and your issue is to fix your windows update, it's somehow logical someone ask it move as all windows support threads.
you shouldn't be scared about the report, but you should be scared your thread end in OTW

NeddySeagoon · Posted: Sun May 21, 2017 8:31 pm Post subject:

This tread started off in OTW.

Several mods/admins have contributed to it and its still in Other Things Gentoo.
Read into that what you will.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.